Scaffold Provides Biodegradable Structure

Scaffold Provides Biodegradable Structure

Results show that human embryonic stem cells grow and multiply readily on the structure. "The major challenge for stem cell therapy today is it's very difficult to make a lot of them with high purity," said lead author Miqin Zhang, professor of materials science and engineering at the University of Washington (UW). "So far it seems like this material is very good for stem cell renewal."

Medical researchers hope to someday use stem cells to grow new tissues and organs. Key to the research is the fact that new cells maintain the property that holds medical promise – the ability to differentiate into any of the more than 220 cell types in the adult human body. Growing the cells in three dimensions better resembles conditions in the human body. It also allows mass production, which will be needed for any clinical applications.

"Three-dimensional scaffolds are an active area of research," said Carol Ware, a UW professor of comparative medicine. "They are not commonly used yet, but will be important to transition embryonic stem cells to the clinic. To date, nobody has found a perfect matrix."
Zhang's cylindrical scaffold is made of chitosan, found in the shells of crustaceans, and alginate, a gelatinous substance found in algae. Both have a structure similar to the matrix that surrounds cells in the body, to which cells can attach. “Different processing techniques can make the scaffold out of interconnected pores of almost any size,” said Zhang.

Researchers first seeded the scaffold with 500,000 embryonic stem cells, and after 21 days the scaffold was completely saturated. The cells infiltrated the structure unlike other materials where cells often grow only on the surface. To retrieve the cells, researchers immersed it in a mild solution. The structure is biodegradable and so dissolved to release the stem cells. One also could implant the stem cell-covered scaffold directly into the body.

Zhang's group is now working to build a scaffold larger than the current dime-sized prototype, and is collaborating with the UW's Institute for Stem Cells and Regenerative Medicine and UW School of Medicine to try growing different types of stem cells, including those from umbilical cord blood and bone marrow, in the material. They will try to get the resulting cells to differentiate into bone, neuron, muscle and liver cells.